(1) Field of the Invention
The present invention relates to a light emitting display apparatus, and particularly relates to a technology for improving color reproducibility.
(2) Related Art
Recently, light emitting display apparatuses that drive self luminous devices by means of thin film transistors (hereinafter also called “TFT”) are receiving attention as display devices having high efficiency, high definition, low power consumption, and high-speed response.
Among such light emitting display apparatuses, those having a structure of causing organic light emitting devices stacked on a TFT substrate to emit light, and extracting the light highly efficiently in a direction of a so-called top side (i.e. opposite direction to a side of the TFT substrate on which TFTs, wiring, and so on, are provided) are under development. This type of light emitting display apparatus is called a top-emission organic electroluminescence panel. Hereinafter, an organic electroluminescence panel is simply referred to as “organic EL panel”.
Organic EL panels obtain white light by synthesizing two lights each having complementary color to the other. Particularly in a top-emission organic EL panel, white light obtained from organic light emitting devices is outputted towards the aforementioned top side direction. Then color filters provided ahead in the direction are used to selectively separate the three primary colors of the white light by transmission, thereby realizing color display. Such a top-emission organic EL panel yields characteristics such as high light emitting efficiency and brightness in resulting pictures, in addition to general characteristics of the organic EL panels such as realization of a thin body and a wide viewing angle.
One type of top-emission EL panels has a resonant structure that strengthens light of a particular wavelength by making a position of a resonance frequency coincide with a wavelength peak position of light, as disclosed by Japanese Laid-open Patent Application No. H07-78689 for example.
However, as mentioned above, an organic EL panel obtains white light by synthesizing two lights each having complementary color to the other, and the three primary colors differ in luminous intensity. Therefore it is difficult to set chromaticity of white light to desired level.
For example, suppose a case where blue light and orange light, each having a complementary color to the other, are emitted and synthesized, and the luminous intensity of each primary color component included in the two lights is measured. Some results show (as in FIG. 4) that before transmission through a color filter, the blue region and the red region of the spectrum show large luminous intensity in emitted color, but the green region situated therebetween shows weak luminous intensity.
In such a case, even after color-filter transmission, red light and blue light will have stronger luminous intensity than green light.
Accordingly, after synthesizing the three primary colors in such a state, resulting white will be a little purplish, for example. This means that white having desirable chromaticity (i.e. pure white) cannot be obtained, impairing color reproducibility in color display based thereupon.
For example, a red light obtained after transmission of a red color filter will have undesirable reproducibility because its source light included in the white is a result from the synthesized lights, and not a single wavelength light.